OSLO, Norway — Police are increasingly certain that mass killer Anders Behring Breivik acted alone, but are leaving no stone unturned in the hunt for collaborators as they try to close one of the bloodiest chapters in Norway's history.

Breivik, 32, killed eight people in a bomb attack in central Oslo last Friday and then shot 68 at an island summer camp for the ruling Labor Party's youth wing.

He has told police he was part of a network in his self-styled "crusade" against Islam and multiculturalism — but Norwegian authorities doubt this.

"So far we have no indication that he has any accomplices or that there are more cells," the head of the Norwegian Police Security Service, Janne Kristiansen, told Reuters on Wednesday. His claim was likely to have been a play for publicity, she said.

Kristiansen said there would be no let-up in hunting Breivik's possible partners, however unlikely, or in police monitoring of extremists.

"As long as there is a tiny chance...we have to investigate it -- that is our main focus," said Kristiansen, who added that Breivik was "too calculated, too focused" to be considered insane.

Norway agreed on Wednesday to review security and the police response to the killings.

"It's important to clarify all aspects of the attacks to learn lessons from what has occurred," Prime Minister Jens Stoltenberg said after parliamentary leaders agreed to appoint an independent commission to review the attack after a period of mourning.

Critics have questioned whether the police acted too slowly to the shooting spree in Utoya, which went on for about 90 minutes before Breivik was arrested, and whether security in the Nordic nation is too lax.

"(Police) organization and capacity will be part of an evaluation,'' Stoltenberg said. He expected the attacks to stimulate political engagement among his compatriots, he said.

Asked about Breivik's claim of affiliation to a "Knights Templar" group, Kristiansen said it had existed at some point, but that security services have had no knowledge of it for a few years. She declined to disclose any more information.

"I think the U.K. was the biggest group [of recipients]," Tangur Veys said. "There were people from Italy, France, Germany ... but the U.K. was the biggest number."

The Guardian cited reports that the domestic extremism unit at the Britain's Scotland Yard, which is investigating Breivik's alleged links to the U.K., has a list of British-based email addresses. The Metropolitan Police refused to confirm the report, The Guardian said.

Separately on Wednesday, police in Germany raided 21 homes and properties linked to suspected right-wing extremists, the prosecutor's office in the state capital Stuttgart said.

The investigation, which was launched in March, was not linked to Norway's attacks, according to the office.

Some 140 police officers took part in the raid in Baden-Wuerttemberg state, seizing weapons, ammunition, drugs and computers from 18 people involved with a group known as "Standarte Wuerrttemberg," which aims to expel all foreigners from Germany.

Insane, calculated or both?
On Tuesday night police destroyed an explosives cache found at a farm rented by Breivik, some 100 miles north of Oslo. They believe he made his bomb using fertilizer which he had bought under the guise of a farmer.

They detonated another cache on Wednesday.

Breivik's lawyer, Geir Lippestad, said his client was probably insane, but it was too early to say if the loner and computer game enthusiast would plead insanity at his trial.

Breivik has confessed to his actions, but denied guilt, saying he was part of a network with two cells in Norway and more abroad that was fighting to save European "Christendom" from the spread of Islam and multi-culturalism.

Breivik, who was remanded in custody for eight weeks on Monday, has been charged under the terrorism act, which carries a maximum penalty of 21 years in jail, but the authorities are considering whether to charge him with crimes against humanity.

Stoltenberg said that Norway had a system allowing sentences to be extended if there were a risk of new crimes.

Below the radar
Both Norwegian and international media have questioned how it has been possible for Breivik to stay below the police radar for so long, having planned the attack for many years.

"This person's strategy is to be below the radar,'' Kristiansen said, when asked how he had avoided being noticed.

"He has done everything on his own in a way that will make the police suspicious of nothing. He has not broken the law. He has had a strategy, and sorry to say he has succeeded in that strategy."

Kristiansen said the security services had warned in their threat assessment earlier this year that right-wing extremism is on the rise in Europe and that there were "some in Norway" but that right and left extremist groups will not pose a "serious threat" to Norway in 2011.

Justice Minister Knut Storberget deflected criticism that police reacted too slowly to the shootings, hailing their work after the attacks as "fantastic."

Many Norwegians seem to agree the police do not deserve reproach for their response. At a rally of more than 200,000 in Oslo on Monday night, people applauded rescue workers.

Trying to move forward
Jittery Norwegians sought to restore some normality five days after the bloodshed, as police reopened some streets around the blast site in Oslo and shops gradually reopened for business.

But two false alarms kept people on edge. A security alert forced the evacuation of Oslo's central station on Wednesday,after a suspicious suitcase was found on a bus. Police said later it was harmless.

In another false alarm, police retracted a search alert for a man who they suspected of sympathizing with Breivik, saying in fact they wanted to detain a mentally ill man with no link to
the killer.

Wolfgang Rattay
/
Reuters

Government minister Rigmor Aasrud plans to return to her office opposite the destroyed government building in Oslo on Wednesday, the first to do so.

In a symbolic effort to promote normalcy, cabinet minister Rigmor Aaserud returned to her office in Oslo's government district where Breivik detonated the bomb on Friday. Her office, in a government complex, was little damaged.

The bomb blew a hole in Stoltenberg's office. For now, he will work from the defense ministry in a different area of Oslo and cabinet meetings will be held in a medieval fort near the waterfront. It is not clear whether the 17-storey prime ministry building will be rebuilt or torn down.

In Stoltenberg's building, which took the brunt of the car bomb, curtains still flapped from broken windows.

Video: Norway nightmare survivors recall horror

Closed captioning of: Norway nightmare survivors recall horror

>>good morning, everyone. new details this morning about the arrest of self-confessed ath terrorist anders breivik. good morning.

>>police add more details. two minutes after they made it to the island, they found breivik on the ground with guns on the ground. police were air frad tofraid to approach him. they thought he was carrying a bomb. he want add lift.

>>he stalked the teenagers like a
shooting gallery
on an island near oslo.

>>really helpless.

>>360 miles to the north, a mother said she experienced the worst hour of her life. 5:42 the afternoon. she got the
text message
from hell.

>>i told police there's a maniac going here.

>>julie was hiding among the rocks while the killer hunted the teenagers and shot them one-by-one.

>> reporter: another text.

>>here she says, i love you. even though i yell at you sometimes. then i really almost broke down. because that was so -- so moving, so touching.

>> reporter: for one hour, mother tried to hold it in. aztecs continued from the
island of death
. then at last, it's over. the killer surrendered to police. her brother had no idea about any of it. later he said he found it odd to get a
text message
from his
twin sister
saying, "i love you."

Under heavily armed police guard, Anders Behring Breivik (left, in red T-shirt) is taken back to Utoya on August 13 to reconstruct his actions during a shooting spree on the island. Breivik is charged with killing 69 people who were attending a summer camp at the lake island after killing another eight people in Oslo with a bomb.
(Trond Solberg / VG - Scanpix Norway via Sipa)
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Breivik travels with police officers on the ferry to Utoya island on August 13. The 32-year-old Breivik described the shootings in close detail during an eight-hour tour on the island, prosecutor Paal-Fredrik Hjort Kraby told a news conference.
(Trond Solberg / VG - Scanpix Norway via Sipa)
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Relatives and friends of the Norway attack victim Tamta Liparteliani gather near a coffin during a funeral in Kutaisi, western Georgia, on August 6. Tamta, a Georgian student, was one of the victims on Utoya island.
(Shakh Aivazov / AP)
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Norway Prime Minister Jens Stoltenberg comforts a relative of Mona Abdninur, 18, during her funeral ceremony in Hoeybraeten, near Oslo, on August 2. Abdninur was one of the 77 people killed by Anders Behring Breivik.
(Stoyan Nenov / Reuters)
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A close friend of Bano Rashid, one of the victims of the massacre on the youth camp of the Norwegian Labour Party, walks ahead of her coffin carrying her portrait as they make their way to her gravesite at Nesodden Kirke, south of Oslo on July 29.
(Odd Andersen / AFP - Getty Images)
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A mourner weeps during the funeral service for Bano Abobakar Rashid at a church in Nesodden, near Oslo, on July 29. Rashid, whose family fled to Norway from Iran in 1996, was one of the victims on Utoya island, where gunman Anders Behring Breivik killed at least 68 people, exactly one week ago.
(Lefteris Pitarakis / AP)
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People pay their respects for the victims in last Friday's killing spree and bomb attack, at a temporary memorial site on the shore in front of Utoya island northwest of Oslo on Wednesday.
(Fabrizio Bensch / Reuters)
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A family drops red roses from their boat into the sea, close to Utoya island, near Oslo, Norway, on July 26.
(Ferdinand Ostrop / AP)
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A sea of flowers and lit candles are placed in memory of those killed in Friday's bomb and shooting attack in front of Oslo Cathedral on Monday, July 25. Hundreds of thousands of Norwegians packed city centres across the country to pay tribute to the 76 people killed in twin attacks last week. Picture taken with fish-eye lens.
(Fabrizio Bensch / Reuters)
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People comfort each other outside Oslo City Hall as they participate in a "rose march" in memory of the victims of Friday's bomb attack and shooting massacre on Monday, July 25.
(Aas, Erlend / AP)
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People gather outside Oslo City Hall to participate in a "rose march" in memory of the victims of Friday's bomb attack and shooting massacre in Norway, Monday.
(Emilio Morenatti / AP)
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Elizabeth Amundsen holds a rose and cries as thousands of people gather at a memorial vigil following Friday's twin extremist attacks on Monday in Oslo, Norway.
(Paula Bronstein / Getty Images)
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Anders Behring Breivik, left, the man accused of a killing spree and bomb attack in Norway, sits in the rear of a vehicle as he is transported in a police convoy leaving the courthouse in Oslo on July 25. A judge ordered eight weeks detention for Breivik.
(Jon-Are Berg-Jacobsen / Aftenposten - Scanpix Norway via Reuters)
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People stand outside the courthouse where Anders Behring Breivik is due to appear in Oslo on July 25.
(Cathal McNaughton / Reuters)
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A couple react as they pay their respects at a sea of floral tributes for the victims of Friday's attacks, outside the cathedral of Oslo on July 25.
(Cathal McNaughton / Reuters)
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People, including relatives of a victim in the center of the picture, gather to observe a minute's silence on a campsite jetty on the Norwegian mainland, across the water from Utoya island, on July 25. People have been placing floral tributes in memory of those killed in the shooting massacre.
(Matt Dunham / AP)
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People stand in front of the Domkirke church in central Oslo on July 25. The bombing of government buildings in Oslo and the subsequent shooting spree at a political youth camp on Utoya island on 22 July have claimed more than 90 lives with the death toll still feared to rise.
(Joerg Carstensen / EPA)
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French police officers work around the house of Jens Breivik, the father of Anders Behring Breivik, in Cournanel, southern France, on July 25. Anders Behring Breivik is reported to have admitted to Friday's shootings at a youth camp and a bomb that killed seven people in Oslo's government district, but to have denied any criminal guilt.
(Bob Edme / AP)
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Norwegian Prime Minister Jens Stoltenberg, left, hugs Queen Sonja as King Harald, right, looks on outside a government building in Oslo on July 24.
(Wolfgang Rattay / Reuters)
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Three roses float in Tyrifjord Lake near a makeshift memorial for the victims of the massacre on Utoya island on July 24.
(Britta Pedersen / EPA)
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Rescue personnel continue in their search for the missing in Tyrifjor lake, just off Utoya island July 24.
(Fabrizio Bensch / Reuters)
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Survivors and relatives of a shooting rampage on the Utoya island mourn following a memorial service in the Oslo cathedral July 24.
(Wolfgang Rattay / Reuters)
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German Marcel Gleffe stands on Utvika camping ground in front of Utoya Island, Norway, July 24. According to news sources, Gleffe, who has a military background, saved up to 30 youths from the Utoya island shooting. Reports state that he was on holiday with his family at a campground across the water from Utoya when he heard the gunfire. He and others reportedly jumped into boats and began ferrying people escaping the island to safety.
(Britta Pedersen / EPA)
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Adrian Pracon, one of the survivors of the Utoya island massacre, speaks from his bed at Ringerike hospital on July 24. He pretended to be dead, and was able to survive with a gunshot wound in his shoulder.
(Steinar Schjetne / EPA)
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A combination of images shows Anders Behring Breivik, the man identified by Norwegian police as the gunman and alleged bomber behind the attack on government buidlings and the Labour party youth camp in Oslo on July 22 . Breivik told police he acted alone in the attack he had planned over many months.
(Facebook / YouTube / AFP - Getty Images)
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Utoya island, located 40 kilometers southwest of Oslo, is seen in the background as people light candles on July 23, in memory of the victims of the July 22 shooting spree on the island.
(Jonathan Nackstrand / AFP - Getty Images)
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Members of the police and army carry out searches on a farm rented by Anders Behring Breivik in the small rural region of Rena, 93 miles north of Oslo, July 23. Breivik was arrested after Friday's massacre of young people on a tiny forested holiday island that was hosting the annual summer camp for the youth wing of Norway's ruling Labour party. The 32-year-old Norwegian was also charged for the bombing of Oslo's government district that killed seven people hours earlier.
(Cathal McNaughton / Reuters)
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Family members and survivors react as Norwegian King Harald and Queen Sonja (not seen) arrive to comfort them outside a hotel northwest of Oslo July 23.
(Fabrizio Bensch / Reuters)
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A boat of rescue services is seen near the bodies of victims covered with white blankets resting at the shore of Utoya island following a July 22 shooting spree at the island, west of the capital Oslo, Norway, July 23.
(Kristoffer Oeverli Andersen / EPA)
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The shattered windows of a government building are seen on July 23 in Oslo, following Friday's bombing.
(Vegard Grott / Scanpix Norway via Reuters)
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People gather outside the Oslo Cathedral to mourn and show their respect for the victims of the July 22 shooting at a Norwegian Labour Youth League camp, July 23.
(Jan Johannessen / AFP - Getty Images)
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People embrace inside a hotel where relatives of victims and survivors of the shooting which took place at a meeting of the youth wing of Norway's ruling Labour Party on Utoya island gather in Sundvollen on Friday.
(Fabrizio Bensch / Reuters)
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Emergency services are seen on Utoya island searching for the missing after a shooting took place at a meeting of the youth wing of Norway's ruling Labour Party on Friday.
(Str / Reuters)
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A wounded woman is brought ashore opposite Utoya island after being rescued from a gunman who went on a killing rampage targeting participants in a Norwegian Labour Party youth organisation event on the island on Friday.
(Svein Gustav Wilhelmsen / AFP - Getty Images)
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A SWAT team aim their weapons while people take cover during a shoot out at Utoya island, some 40 km south west of the capital Oslo on Friday.
(Jan Bjerkeli / AFP - Getty Images)
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An aerial view of Utoya Island taken July 21. A gunman opened fire on youths at a camp on the island, killing at least nine. Police arrested a suspect, a Norwegian, and said he was linked to the bomb blast in Oslo.
(Lasse Tur / AP)
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Still images taken from surveillance camera footage show the moment the bomb blast struck the Digital Impuls store in Oslo on Friday July 22, as glass shatters and people run out of the store.
(Reuters Tv / Reuters)
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Smoke pours from a building in the center of Oslo, Norway, on Friday, July 22, after an explosion that damaged several buildings, including the prime minister's office, shattering windows and covering the street with documents. The bombing was linked to a nearly simultaneous attack on a youth camp northwest of Olso in which a man dressed as a policeman opened fire on young people.
(Thomas Winje ØIjord / AP)
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An injured woman is helped by a man at the scene of the explosion. The blast damaged government buildings in central Oslo, including Prime Minister Jens Stoltenberg's office.
(Scanpix Norway / Reuters)
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Editor's note:
This image contains graphic content that some viewers may find disturbing.